Political Leader Is Held in Connection to the Irish Republican Army's 1972 Killing of a Belfast Widow

Police in Northern Ireland arrested Sinn Féin leader Gerry Adams on Wednesday in connection with the 1972 Irish Republican Army killing of Jean McConville, one of the most high-profile unsolved murders of the bloody period of sectarian strife known as the Troubles.

Mr. Adams, 65 years old, who has repeatedly denied having any part in the killing of the 37-year-old widow and mother of 10, said he had voluntarily presented himself for...